A dolmen (/ˈdɒlmɛn/) is a type of single-chamber megalithic tomb, usually consisting of two or more vertical megaliths supporting a large flat horizontal capstone or "table". Most date from the early Neolithic (4000–3000 BC) and were sometimes covered with earth or smaller stones to form a tumulus. Small pad-stones may be wedged between the cap and supporting stones to achieve a level appearance. In many instances, the covering has weathered away, leaving only the stone "skeleton" of the mound intact.